1. Field of the Invention
The present invention relates to a toner for use in an image forming method, such as an electrophotographic method, an electrostatic recording method, and a toner jet method.
2. Description of the Related Art
In recent years, a rapid increase in the speed of laser printers and copiers using electrophotography has required a toner having excellent developability, transferability, and low-temperature fixability. In particular, improvement in low-temperature fixability leads to a reduction in power consumption and is essentially required in the development of an environmentally-friendly toner.
With growing markets for laser printers and copiers, a toner is required to reliably provide performance even when stored or used in a high temperature and high humidity environment. Furthermore, the temperature in an apparatus tends to increase because of the miniaturization of the apparatus and a silent, fan-less design. So, a toner is required to have higher heat resistance.
To meet such requirements, toners with a core-shell structure, in which surfaces of toner particles are designed to have heat resistance and durability and cores of toner particles are designed to have low-temperature fixability, have been studied.
Japanese Patent Laid-Open No. 2008-268366 discloses a toner containing a low-molecular-weight polar vinyl resin having a specific acid value, the resin being arranged between the core and the shell of each toner particle, whereby the toner can form an image with high glossiness even when fixed at a low temperature and has high durability even under severe conditions of use. Japanese Patent Laid-Open No. 2009-151235 discloses a toner having excellent low-temperature fixability and durability and containing toner particles produced in an aqueous medium, in which the glass transition temperature Tg of cyclohexane-insoluble matter in tetrahydrofuran-soluble matter is a specific value.
However, a toner is now required to have a higher level of heat resistance. It is difficult to produce a toner having durability that meets the level in the related art described above. Furthermore, it is difficult to produce a toner that has high durability and that simultaneously meets high developability, high transferability, and low-temperature fixability.